| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | Peter Geoghegan <pg(at)bowt(dot)ie> |
| Cc: | Masahiko Sawada <masahiko(dot)sawada(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: xid wraparound danger due to INDEX_CLEANUP false |
| Date: | 2020-05-06 20:06:25 |
| Message-ID: | 20200506200625.GA24192@alvherre.pgsql |
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| Lists: | pgsql-hackers |
On 2020-May-06, Peter Geoghegan wrote:
> Also, do we really want to skip summarization of BRIN indexes? This
> cleanup is rather dissimilar to the cleanup that takes place in most
> other AMs -- it isn't really that related to garbage collection (BRIN
> is rather unique in this respect). I think that BRIN might be an
> inappropriate target for "index_cleanup off" VACUUMs for that reason.
>
> See the explanation of how this takes place from the docs:
> https://www.postgresql.org/docs/devel/brin-intro.html#BRIN-OPERATION
Good question. I agree that BRIN summarization is not at all related to
what other index AMs do during the cleanup phase. However, if the
index_cleanup feature is there to make it faster to process a table
that's nearing wraparound hazards (or at least the warnings), then I
think it makes sense to complete the vacuum as fast as possible -- which
includes not trying to summarize it for brin indexes.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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